Vehicles such as automobiles typically have several lamps including head lamps and fog lamps. These lamps generally include a housing supporting a reflector (which is typically mounted within the housing on a mounting bracket) and a lens with a bulb mounted therebetween, the entire lamp assembly being attached to the vehicle. Examples of such a configuration are shown in U.S. Pat. Nos. 5,707,133 and 6,974,231 to Burton. Once the lamp assembly has been manufactured and installed into a vehicle, the lamp must be adjusted to the proper aim. Typically the adjustment is in both the vertical and horizontal directions although, depending on the type of lamp and applicable regulations, adjustment in only one direction may be required. As a result of accidents, maintenance, and normal vibrations and wear, the aim of the lamp may need to be occasionally adjusted during the lifetime of the vehicle as well.
One method of adjusting the aim of the lamp involves using an adjuster. The adjuster can be formed as part of the mounting bracket, part of the housing, or can be a separate part between the housing and the mounting bracket (or the reflector directly if no separate mounting bracket is used). One known type of adjuster includes a housing and an output shaft extending therefrom. The output shaft is engaged to the reflector directly or to a mounting bracket on which the reflector is positioned. Actuation or operation of the adjuster causes the output shaft to move. Such movement causes the mounting bracket and/or reflector to pivot or otherwise move with respect to the housing, thereby adjusting the aim of the lamp. One example of this type of adjuster is disclosed in U.S. Pat. No. 6,773,153 to Burton, the disclosure of which is incorporated herein by reference for all purposes. The housing of the adjuster in this Burton design has an opening and a gear positioned inside the housing. The gear is functionally engaged to a ball stud. An input shaft is positioned in the opening and interacts with the gear. Actuation of the input shaft results in rotation of the gear and engaged ball stud. The gear translates actuation of the input shaft into axial movement of the ball stud and its ball stud end. Numerous variations exist on this general concept.
Having end-of-travel clutching regardless of a resistance force present is desirable to both achieve a minimum required amount of travel for aiming while also preventing damage to adjuster function, disengagement or damage to the headlamp components, the reflector and mounting bracket in particular. One method for accomplishing end of travel clutching is disclosed in U.S. Pat. No. 6,773,153 to Burton. Some headlamps have a high resistance force to overcome during aiming. A common cause for this is resistance from rubber reflector seals. Thus, it is desirable to have an adjuster that includes end of travel clutching regardless of resistance present. It is also desirable to assure aiming function under resistance from headlamp components that may increase the torque required for adjustment, especially at the end of travel. In particular, after clutching has occurred at the end of travel, it is important to be able to re-engage the ball stud in the return direction without failure of the clutching features due to an increased adjustment torque. Preventing failure of the clutching features during re-engagement avoids a ‘stuck’ (i.e., inoperable) adjuster that is unable to aim. Having a high failure torque resistance of the clutching features in this direction is desirable and is generally referred to as “re-engagement torque.” Clutching torque on the other hand is the torque generated as the gear rotates while disengaging from the ball stud being held fixed. Clutching torque needs to be limited and kept low enough in order to prevent failure of the thread stop holding torque or another means of holding the ball stud fixed at the end of travel, such as, but not limited to, thread interference between the ball stud and housing.
Accordingly, a need exists for an improved adjuster that solves these and other deficiencies in the prior art. It will be understood by those skilled in the art that one or more aspects of this clutching mechanism can meet certain objectives, while one or more other aspects can lead to certain other objectives. Other features, benefits and advantages of the clutch force adjuster mechanism will be apparent in this summary and descriptions of the disclosed embodiment, and will be readily apparent to those skilled in the art. Such features, benefits and advantages will be apparent from the above as taken in conjunction with the accompanying figures and all reasonable inferences to be drawn therefrom.